Gen. Math. Notes, Vol. 27, No. 1, March 2015, pp. 55-68 ISSN 2219-7184; Copyright © ICSRS Publication, 2015 www.i-csrs.org Available free online at http://www.geman.in Numerical Study for Heat Transfer in Symmetric Porous Channel with Expanding or Contracting Walls and Slip Boundary Condition K. Raslan1 and Zain F. Abu Shaeer2 1,2 Department of Mathematics, Faculty of Science Al-Azhar University, Egypt 1 E-mail: kamal_raslan@yahoo.com 2 E-mail: zainfathi@hotmail.com (Received: 22-11-14 / Accepted: 1-2-15) Abstract The homotopy analysis method (HAM) is implemented to obtain the approximate solutions of the nonlinear evolution equations in mathematical physics. The results obtained by this method have a good agreement with one obtained. It illustrates the validity and the great potential of the homotopy analysis method in solving partial differential equations. Keywords: HAM, Porous channel; Expanding and contracting walls Slip boundary condition; Heat transfer. 1 Introduction The flow in channels and in circular pipes with permeable walls has received considerable attention in the past few years. The earliest work of steady flow 56 K. Raslan et al. across permeable and stationary walls can be traced back to Berman [1], who showed that the governing equations can be reduced to single fourth-order nonlinear ordinary differential equation which includes permeation Reynolds number ℛ , and associated solution can be obtained. Laminar flow studies in porous pipes or channels with expanding or contracting walls have received considerable attention due to their applications in biophysical flows. These include the model of pulsating diaphragms, filtration, blood flow and artificial dialysis, binary gas diffusion, the model of air and blood circulation in the respiratory system. In order to simulate the peristaltic motion by successive wall contractions and expansions. Uchida and Aoki [15] first examined the viscous flow inside an impermeable tube with contracting cross sections. Ohki [20] investigated the unsteady flow in a porous semi-infinite tube, whose elastic wall had a varied length and a stable cross section. To simulate the laminar flowed in cylindrical solid rocket motors, Goto and Uchida [4] analyzed the laminar incompressible flow in a semi-infinite porous pipe, whose radius varied with time. Bujurke et al. [3] obtained a series solution to the unsteady flow in a contracting or expanding pipe. Majdalani et al. [6] obtained an exact similarity solution to the viscous flow with small wall contractions or expansions and weakly permeability. Dauenhauer and Majdalani [5] obtained a numerical solution and Majdalani and Zhou [7] got both numerical and asymptotical solutions for moderate to large Reynolds numbers. Srinivasacharya [14] obtained a numerical solution to the flow and heat transfer of couple stress fluidin a porous channel with expanding and contracting walls. Si et al. [13] obtained analytic solutionto the micro-polar-fluid flow through a semi-porous channel with an expanding or contracting wall. Dinarvand [10] studied viscous flow through slowly expanding or contracting porous walls with lowseepage Reynolds number: a model for transport of biological fluids through vessels. No-slip condition was no longer valid at the permeable surface. Some of both experimental and theoretical studies stated that slip could not be ruled out as a significant element in the understanding of certain flow peculiarities [17]. Beavers, Joseph [2] reported mass efflux experimentsand proved the existence of a non-zero tangential (slip) velocity on the surface of a permeableboundary. Using a statistical approach, Saffman [12]derived a form for the slip velocity. Isenberg [8] posited slip for all practical purposes in his study of blood flow in capillary tubes. However, verylittle reports were found in literature for micropolar fluids with expanding or contracting walls andslip boundary condition. Bennett [11] reported that microscopic examination of blood flowing pasta glass wall shown slipping (skidding) of red cells in contact with the wall. Chellam et al. [9] investigated the effect on fluid flow and mass transfer with slip at a uniformly porous boundary. Recently, Zhang and Jia [18, 19] discussed the Navier-Stokes equations with firstorder and second-order accurate slip boundary conditions for describing the twodimensional gaseous steady laminar flow between two plates. Ramos [16] obtained an asymptotic analytical solution of channel flows of incompressible Numerical Study for Heat Transfer in… 57 fluids with a slip length that depended on the pressure and/or the axial pressuregradient. The series solutions are presented by HAM developed by Liao [21-23], which has been successfully applied to several nonlinear problemsby Hayat, Noor and Hashim [25, 26]. In this paper, the effects of different parameters, especially expansion ratio and slip coefficient, on velocityand temperature are studied and shown graphically. The main goal of this paper is to find the numerical solutions for the heat transfer insymmetric porous channel with expanding or contracting walls and slip boundary conditions. Thesecond section will give statement of the problem and governing equations. In section3, computations by Homotopy analysis method. Finally, the graphs for velocity components and heat transfer presented for different values of the fluid parameters are plotted and discussed. 2 Statement of the Problem and Governing Equations Consider the unsteady two-dimensional motion of an incompressible fluid with heat transfer in a porous semi-infinite channel with expanding or contracting walls with slip boundary condition. The distance 2 (t) between the porous walls is much smaller than the width and length of the channel. One end of the channel is closed by a complicated solid membrane. Both walls have equal permeability and expand or contract uniformaly at a time-depended rate ( ). As shown in Fig. 1, a coordinate system may be chosen with the origin at the center of channel. Take and y to be co-ordinate axes parallel and perpendicular to the channel walls and assume u and v to be the velocity components in the and y directions respectively and θ is the temperature. Under these assumptions, the governing equations are expanded as follows [27]. + "# "-. # 0 / $ "# +% 0 / $ =0 +% +% $ +& 0 / +& +& ' =− ' =− , ) ) ' = * 14 # ' + # + *+ , % + *+ & + , , 0 ' 3 + 4+ , 5, 7 (1) 58 K. Raslan et al. Figure1: Coordinate system and bulk fluid motion A general infinitesimal group of transformations under which given partial deferential equations are invariant [27], the equations (1) are a set of linear deferential equations. Ref [27] completed transforms as %= 89 8: , & = − 8; , 89 (2) And the stream function takes the form, [24, 27] <= =(>), % = ?@ ? , & = −=, (3) These transforms change the second equation in (1) to, AB C A:B + α #y AE C A:E + 2 A:F ' + ℛ #G AF C AE C A:E − A: A:F ' = 0, AC AF C (4) He Suggest that the form of temperature take as 5 = H( , >) = I(>) + , J(>), (5) During the assumption of the third and fourth equation in (1) become KJ K, = K= K,J + L N(O > + ℛ =) + Q S T − 2ℛ J U = 0, M P R P K> , K> K> , K> , ? ?@ , F + LM 1(O > + ℛ P =) ? + 4QR #? ' 3 + 2 J = 0, ?F V ?V (6) With the boundary conditions K , =(1) K=(1) = −X , K> K> , =(1) = 1, I(1) = 1, J(1) = 0, Numerical Study for Heat Transfer in… ?F @(Y) ? F = 0, =(0) = 0, I(0) = 5, , Where ℛ = and Ea = Z[\ Re /f J(0) = 0,(7) is permeation Reynolds number, P_ = Z[\ F 59 ] `ab c is Prandtl number is Eckart number. The wall permeance or injection coefficient A is defined as h = i, it is a measure of wall permeability. It will be started to solve Z the nonlinear equations (4) and (6) with the boundary conditions. 3 ℛ Computations by Homotopy Analysis Method [21-23] From the rule of solution expression and the boundary conditions (7) it is straightforward to choose the following initial guesses. =Y (>) = , JY (>) = (j klmn F ) ,(olm k) , and IY (>) = 5, + (1 + 5, )>, (j klmn F ) ,(olm k) (8) The linear operators are selected as ℒo = B , ℒ, = ?B @ ? F , and ℒ m = ?F q ? ?F V , ? F (9) These operators satisfy the following properties: ℒo (ro > m + r, > , + rm > + rs ) = 0, ℒ, (rt > + rj ) = 0, and ℒm (ru > + rv ) = 0, Where rw (x = 1 − 8) are the constants. (10) Upon making use of above definitions, we construct the zero-order deformation problems (1 − z)ℒo {= − =Y | = z ℏ ℵo {= , Ĵ |, = € (1, z) = −X = €€ (1, z), = (1, z) = 1, = €€ (0, z) = 0, = (0, z) = 1, (1 − z)ℒ, (Ĵ − JY ) = z ℏ ℵ, {= , Ĵ |, Ĵ (1, z) = 0, Ĵ (0, z) = 1, (1 − z)ℒm (• − •Y ) = z ℏ ℵm (= , J, I‚), I‚(1, z) = 1, I‚(0, z) = 5, , (11) (12) (13) (14) (15) (16) 60 K. Raslan et al. ℵo {= , Ĵ | = B@ B ℵ, {= , Ĵ | = 2ℛP Ĵ (>, z) 0 , χ| = ℵm {G + O #> F q( ,)) F ) @ ( ,)) E@( ,)) E +2 F@( ,)) F ' + ℛP # + LM #(O > + ℛP = (>, z)' E@( = (>, z) − ,)) E q( ,)) + QR ( F@( @ ( ,)) F @ ( ,)) F ' (17) ) − ,)) , F (18) 0(y, p) ∂, ζ‚(y, p) ∂ζ‚(y, p) ∂G 0 (y, p)' + P_ ‡#α y + ℛ G + 4Ea ( ), ˆ + 2χ(y, p), , ∂y ∂y ∂y (19) If z ∈ [0, 1] is an embedding parameter and ℏ are the nonzero auxiliary parameters then the zeroth-order deformation problems can be constructed as [15] respectively. Using Taylor’s theorem, we can write • = (>, z) = =Y (>) + ∑Ž ••o =• (>)z , =• (>) = •! • Ĵ (>, z) = Ĵ Y (>) + ∑Ž ••o Ĵ • (>)z , Ĵ • (>) = , o ‘@ ( ,)) o ‘ q( ,)) •! o • ‚ ‚ I‚(>, z) = I‚Y (>) + ∑Ž ••o I• (>)z , I• (>) = •! )‘ ‘V ( )‘ , ,)) )‘ , (20) (21) (22) The convergence of the two series is strongly dependent upon ℏ. Assume that ℏis chosen so that the series (20-22) are convergent at z = 1. From Equations (2022), we have =(>, z) = =Y (>) + ∑Ž ••o =• (>), (23) J(>, z) = JY (>) + ∑Ž ••o J• (>), (24) I(>, z) = IY (>) + ∑Ž ••o I• (>), (25) Differentiating Equations (14) and (16) m times with respect toz, then setting z = 0 and finally dividing them by m! , we obtain the following m“” -order deformation problems. ℒo (=• (>) − •• =•no (>)) = ℏ ℜ@• (>), € (1) €€ (1), €€ (0) =• = −X =• =• (1) = 0, =• = 0, and =• (0) = 0, €€€ € €€ €€€ €€ ℜ@• (>) = =•no + O(> =•no + 2 =•no ) + ∑•no —•Y ℛ P (=•n—no =— − =•n—no =— ), (s) ℒ, (J• (>) − •• J•no (>)) = ℏ ℜ• (>), q (26) (27) (28) (29) Numerical Study for Heat Transfer in… J• (0) = 0, J• (1) = 0, 61 (30) ™ € ˜no € € ℜ˜ (y) = χ€€ ˜no + P_ (( α y)χ˜nšno + ℛ ∑š•Y (G˜nšno χ˜ − 2χ˜nšno Gš ) + €€ €€ Ea G˜nšno Gš ), (31) ℒm (ζ˜ (y) − •˜ ζ˜no (y)) = ℏ ℜ˜ (y), ζ˜ (0) = θ, , ζ˜ (1) = 1, › (32) (33) › ˜no € € € € ℜ˜ (y) = ζ€€ ˜no + P_ [( α y)ζ˜nšno + ℛ ∑š•Y (f˜nšno ζ˜ + 4Ea G˜nšno Gš ] + (34) 2χ€€ ˜no , Where •• = • 0, 1, ž ≤ 1, 7 ž > 1. (35) The general solutions of Equations (26), (29) and (32) are ∗ (>) =• (>) = =• + ro + r, > + rm > , + rs > m ), ∗ (>) J• (>) = J• + rt + rj >), ∗ (>) I• (>) = I• + ru + rv >), (36) (37) (38) ∗ (y), ∗ (y) in which G˜ χ˜ and ζ∗˜ (y)denote the special solutions of Equations (26), (29) and (32) and the integral constants C£ (i = 1 − 8) are determined by employing the boundaryconditions (27),(30) and(33).In this way, it is easy to solve the linear nonhomogeneous. Equations (26), (29) and (32) by using Mathematicaone after the other in the order m = 1, 2, 3, . . .. =(>) = (uujojYY(olm¦)§ (−3880800(−3 + > , − 6X)(1 + 3X)s − 55440(−1 + > , )(1 + 3X), (ℛP (−2 + > , + > s + 3(−6 + > , + > s )X) + 21O(1 + 3X)(−1 − 7X + > , (1 + 3X)))ℏ + (−1 + > , )(−2772O(1 + 3X), (25> s O(1 + 3X), − 210(1 + 3X)(1 + 7X) − 2> , (1 + 3X)(−105 + 19O + 15(−21 + 8O)X) + O(13 + 3X(52 + 285X))) + 6ℛP, (703 + 14> v (1 + 3X), − 7> j (1 + 3X), (53 + 110X) − > , (1 + 3X)(173 + 7X(71 + 330X)) − > s (1 + 3X)(173 + 7X(71 + 330X)) + X(11248 + 21X(2063 + 3630X))) − 77¬(1 + 3X)(65> j O(1 + 3X), + > , (1 + 3X)(360(1 + 3X) + O(227 + 681X + 3240X , )) + > s (1 + 3X)(360(1 + 3X) + O(389 + 15X(121 + 216X))) − 3(240(1 + 3X)(1 + 9X) + O(227 + X(3178 + 3X(3793 + 6480X))))))ℏ, )), (39) 62 K. Raslan et al. If we take ϕ → 0, we get =(>) = S n E O,( ² § , + m − to E , + 3O # § sY − E ,Y + ' + ℛP # sY ¯ ,vY − m E ,vY + osY + O(− omℛi ° ± ,YojY − + tjYY + ,t,YY − mmjYY)'³ + ℛP, (²,sYY − mmjY + o²jYY + oYuvYY − o,²mjYY) + ,vYY ² ¯ 4 n ¯ oo, ² § + sYY ,,u E ,vYY ,,u + om ), ´´ µF ° m ¯ ,vYY um E uYm (40) Numerical Results and Discussion Our computations show that the series solutions converge in the whole region of ywhenℏ¶ = ℏ· = −1,. This section deals with the graphics and the interpretation of the dimensionless wall dilation rateα and the slip coefficientϕ, on the and y components of the fluid velocity and heat transfer distributions. Table (1), figures 2(a) and 2(b) present the comparison of self-axial velocity u/x profiles between the HAM solutions and Ref. [24] analytical results for α = ±0.5, X = 0. Figures (3–5) show the effect of slip coefficient on the velocity components and the temperature distributions. We can observe that the slip coefficient ϕ has obvious influence on the velocity and the temperature. Fig.2 shows that the axial velocity is a decreasing function of X near to the center. However, it is an increasing function of ϕ near to the walls. However, with the increase in ϕ , the influence of X on the velocity and the temperature becomes smaller. We can also find that the radial velocity is a deceasing function ofX in fig. 3. Fig.4 show that the effect of the slip coefficient ϕ on temperature θ, it is obvious that as ϕ increasing the temperature θ decreasing.The influence of the wall expansion ratio α on velocity component u/x is given in Figures (6–11) for fixed ϕ in case of injectionℛ = 1 and suctionℛ = −1. With the expansion of the wall, the axial velocity increases. The maximum of streamwise velocity lies at the center of the channel whether α is positive and the lower near the wall; however, whether α is negative (contracting wall), increasing contraction ratio leads to lower axial velocity near the center, and the higher near the wall. The axial velocity distribution, in all cases, approaches a cosine profile. Figs. (8 and 11) shows that the effect of the wall expansion ratio α on the temperature θ, It is shown that the temperature is increasing function with α for injection and suction. Figs. (12-14) shows that the effect of the Eckert number Ea , Prandtel number P_ and the initialtemperatureθ, on the temperature distribution, we find that the temperature is increasing function withEa , P_ and θ, . Numerical Study for Heat Transfer in… 63 Table1: Comparison between present work solutions and Ref. [24] for self-axial velocity at ℛ = 5, forX = 0,O = −0.5 and O = 0.5 α = -0.5 α = 0.5, Y Ref[24] Present Percentage error (%) Ref[24] Present Percentage error (%) 0.00 1.5151 1.50268 0.0124254 1.556324 1.5439 0.0124254 0.05 1.51134 1.49901 0.0123324 1.551780 1.53945 0.0123324 0.10 1.50005 1.488 0.0120513 1.538164 1.52611 0.0120513 0.15 1.48118 1.4696 0.0115757 1.515522 1.50395 0.0115757 0.20 1.45465 1.44376 0.0108947 1.483935 1.47304 0.0108947 0.25 1.42038 1.41039 0.00999335 1.443517 1.43352 0.00999335 0.30 1.37826 1.36941 0.00885233 1.394421 1.38557 0.00885233 0.35 1.32817 1.32072 0.00744968 1.336839 1.32939 0.00744968 0.40 1.27002 1.26426 0.00576282 1.271006 1.26524 0.00576282 0.45 1.20371 1.19994 0.00377264 1.197207 1.19343 0.00377264 0.50 1.1292 1.12773 0.00146993 1.115778 1.11431 0.00146993 0.55 1.04651 1.04764 0.00113512 1.027110 1.02824 0.00113512 0.60 0.955722 0.959722 0.00399957 0.931656 0.935656 0.00399957 0.65 0.857047 0.864077 0.00702959 0.829933 0.836962 0.00702959 0.70 0.750818 0.760875 0.0100568 0.722523 0.73258 0.0100568 0.75 0.650349 0.650349 0.0128079 0.610078 0.622886 0.0128079 0.80 0.532795 0.532795 0.0148669 0.493322 0.508189 0.0148669 0.85 0.408567 0.408567 0.0156289 0.373046 0.388675 0.0156289 0.90 0.278066 0.278066 0.014244 0.250109 0.264353 0.014244 0.95 0.141729 0.141729 0.00955104 0.125435 0.134986 0.00955104 1.00 -3.470E-18 0.00000 3.470E-18 3.470E-18 0.00000 3.470E-18 64 Fig (2a): Comparison between present work solutions and Ref. [24] for self-axial velocity profiles at ¿ = 0.5 and ¼À = 5.0. Fig. 3:The effect of the slip coefficient » on the selfaxial velocity component with ¼½ =0.5, ¾=0.2 Fig. 5: The effect of the slip coefficient » on temperture distribution with ¼½ = 1, ¾ =0.5, Âà = 0.5, ÄÅ = 0.7, ÆÇ = 0, È =3. K. Raslan et al. Fig (2b):Self-axial velocity profiles shown over a range of Re at ¾ = −Á. » = Á Fig.4: The effect of the slip coefficient » on the radial velocity component with ¼½ =0.5, ¾=0.2 Fig. 6: The effect of the wall expansion ratio O onthe self-axialvelocity component with ℛ =1, ϕ =0.2. Numerical Study for Heat Transfer in… Fig. 7: The effect of the wall expansion ratio O on the radialvelocity component with ℛ = 1, ϕ=0.2. Fig. 9: The effect of the wall expansion ratio Oonthe selfaxialvelocity component with ℛ = -0.5, ϕ =0.2. Fig. 11: The effect of the wall expansion ratio Oon temperaturedistribution with ℛ =- 1, X =0.2, Q- = 0.5,LË = 0.7, 5, = 0,x=3 65 Fig. 8: The effect of the wall expansion ratio O on temperature distribution with ℛ = 1, X = 0.2, Pr = 0.7, Ec=0.5, θ, = 0, x =3. Fig. 10: The effect of the wall expansion ratio O on the radial velocity component with ℛ = -0.5, ϕ=0.2. Fig. 12:The effect of the Eckart number QR on temperaturedistribution with ℛ = 1, , X = 0.2α =0.5, Pr = 0.7, θ, = 0, x =3. 66 K. Raslan et al. Fig. 13:The effect of Prandle number ÄÅ on temperature distribution with ¼½ = 0.5, Ì = Á. Ç, ¾ =0.5, Âà = 0.5,ÆÇ = 0, È =3. 5 Fig. 14: The effect of ÆÇ on temperature distribution with ¼½ = 0.5, » = Á. Ç, ¾ =0.5, Âà = 0.5, ÄÅ = 0.7, È =3. Conclusion In this paper, the Homotopy Analysis Method has been applied to study the heat transfer in symmetric porous channel with expanding or contracting walls and slip boundary condition equation. 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